Project Background Veterans with PTSD often face a spiral of losses in social functioning and social resources, leading to poor community reintegration. We define community reintegration as activities and participation across a range of life roles, including relationship with spouse/significant other, parenting, education, work, social, leisure, spiritual, civic, self-care, domestic life and economic life. While those who complete evidence-based treatments like Prolonged Exposure (PE) show improvements in social functioning, only 6-11% of Veterans with PTSD start these treatments, and of those, 30-49% drop out. Peer specialists (Veterans who manage mental health challenges and are trained and supervised to support other Veterans in mental health recovery) may provide a way to help more Veterans engage in and complete PE. This research constitutes first steps to learn if supplementing PE with professional peer support may increase the numbers of Veterans who engage in and complete PE; if so, the use of peer support interventions adjunctive to PE may improve rehabilitation outcomes. Project Objectives A multidisciplinary team with expertise in peer support, treatment development, PTSD, qualitative methods, and psychosocial rehabilitation will use Veteran-centered focus group data with existing theory and research to refine an adjunctive intervention called Peer Enhanced Exposure Therapy (PEET). PEET will be designed to improve treatment engagement, treatment adherence, social functioning, and community reintegration among Veterans receiving PE. Aim 1) Refine a preliminary adjunctive intervention manual, training materials, fidelity monitors, and outcome measures for Peer Enhanced Exposure Therapy (PEET) through focus group interviews and expert panel feedback. Aim 2) Pilot test the feasibility and acceptability of the adjunctive intervention. Project Methods For Aim 1, the team will assemble focus groups for a) Veterans who are currently in or have recently dropped out of PE, and b) VA PE providers. Results from qualitative analysis of focus group content will subsequently be evaluated by experts in PE and peer support, to refine components of the treatment manual. The team will then refine the manual, training materials, fidelity monitors, and outcome measures for PEET. For Aim 2 the team will test the intervention by training 2 peer specialists and implementing the intervention for at least 12 Veterans seeking PE treatment. The intervention will be assessed using a) semi structured interviews from Veterans, PE providers, and peer specialists, b) a trial battery of potential outcome measures, and c) peer specialist performance on knowledge tests, skill performance, and fidelity monitors. Results will be used to a) refine the treatment manual and associated materials and b) support Stage II trials.